U.S. patent number 5,452,606 [Application Number 08/281,977] was granted by the patent office on 1995-09-26 for apparatus for measuring wheel positions on a vehicle.
This patent grant is currently assigned to Hofmann Wernstatt-Technik GmbH. Invention is credited to Marco Castelnuovo.
United States Patent |
5,452,606 |
Castelnuovo |
September 26, 1995 |
Apparatus for measuring wheel positions on a vehicle
Abstract
A method and apparatus for measuring wheel positions on a
vehicle involving measurement of certain angular positions of the
vehicle wheel comprises measuring a plurality of different vertical
spacings of a part of the body of the vehicle from the center of
the wheel, and the wheel positions associated therewith. The
measurement values are related to each other to determine a
dependency of the position of the wheel on the level which is
ascertained in that way.
Inventors: |
Castelnuovo; Marco (Milan,
IT) |
Assignee: |
Hofmann Wernstatt-Technik GmbH
(DE)
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Family
ID: |
6442904 |
Appl.
No.: |
08/281,977 |
Filed: |
July 29, 1994 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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962335 |
Oct 16, 1992 |
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Foreign Application Priority Data
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Oct 17, 1992 [DE] |
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41 34 411.1 |
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Current U.S.
Class: |
73/115.07;
33/203; 33/203.18 |
Current CPC
Class: |
G01B
5/255 (20130101); B60G 2200/46 (20130101); B60G
2200/462 (20130101); B60G 2200/4622 (20130101); B60G
2206/93 (20130101) |
Current International
Class: |
G01B
5/24 (20060101); G01B 5/255 (20060101); G01B
005/24 () |
Field of
Search: |
;73/118.1 ;364/559
;33/203,203.12,203.13,203.15,203.17,203.18 |
References Cited
[Referenced By]
U.S. Patent Documents
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4615618 |
October 1986 |
Bailey et al. |
4977524 |
December 1990 |
Strege et al. |
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Primary Examiner: Chilcot, Jr.; Richard E.
Assistant Examiner: McCall; Eric S.
Attorney, Agent or Firm: Cushman Darby & Cushman
Parent Case Text
This is a continuation of application Ser. No. 07/962,335, filed on
Oct. 16, 1992, abandoned, Jul. 29, 1994.
Claims
I claim:
1. An apparatus for determining wheel positions of a vehicle wheel
on a vehicle having a body, comprising:
(a) a detector for measuring angular wheel position
characteristics;
(b) a mounting adaptor for mounting said detector to said vehicle
wheel;
(c) a spacing measuring means for measuring a vertical spacing
between an axis of rotation of said vehicle wheel and a reference
point on said vehicle body, said spacing measuring means being
coupled to said detector;
(d) a computing unit operatively connected to said spacing
measuring means and to said detector, said computing unit
determining a relationship between the measured vertical spacing
and a corresponding angular wheel position characteristic so that
angular wheel positions can be determined relative to a given
vertical spacing; and
(e) an extensible measuring element spanning between said spacing
measuring means and said reference point on the vehicle body.
Description
BACKGROUND OF THE INVENTION
In motor vehicles, in particular vehicles driven by an on-board
engine, which have active and/or semi-active wheel suspension
arrangements by means of which the ground clearance of the vehicle,
or the distance between the underside of the vehicle and the ground
on which it is disposed, is variably adjustable, it is necessary to
determine the level of the vehicle, in order to achieve correct
geometrical wheel position values. The level of the vehicle is
defined by the difference in height of a part of the vehicle which
is supported in sprung relationship on a wheel of the vehicle, for
example the chassis of the vehicle, relative to an unsprung part of
the vehicle, for example a suspension member which is directly
connected to the respective wheel.
Reference will be made at this point to FIGS. 1 and 2 of the
accompanying drawings to illustrate this point in connection with a
wheel suspension arrangement for a motor vehicle wheel.
Referring therefore to FIGS. 1 and 2, reference numeral 14
identifies an unsprung suspension member 14 of the wheel suspension
assembly, which supports a wheel hub assembly 16. An upper strut or
suspension link 15 and a lower strut or suspension link 13 of the
wheel suspension arrangement are pivotally connected to the
suspension member 14. Reference numeral 12 identifies a sprung part
of the vehicle, for example the chassis structure thereof, which is
supported by the two struts or suspension links 13 and 15, by
virtue of the latter being pivotally connected to the part 12 of
the vehicle, with the suitable interposition of springs, dampers
and the like (not shown), on the suspension member 14 which carries
the wheel hub assembly 16. The level of the vehicle which is
indicated at a in FIG. 1 is defined by the difference in height
(h1-h2) of a pivot mounting point 6 for the sprung part 12 of the
vehicle to the lower suspension link 13 and a pivot mounting point
7 of the lower suspension link 13 to the unsprung suspension member
14, in each case in relation to the ground 17 on which the wheel 1
is supported. When the wheel suspension arrangement and the wheel 1
are loaded with the normal weight of the spring-suspended part 12
of the vehicle, the components of the wheel suspension arrangement
and the wheel 1 occupy the position shown in FIG. 1.
If the vehicle and in particular the chassis thereof is loaded with
an additional weight, the components of the wheel suspension
arrangement and the wheel 1 assume the positions shown in FIG. 2,
by virtue of a downed movement of the chassis relative to the
ground 17 on which the wheel 1 is supported. It will be seen that
not only does that cause a change in the level of the vehicle as
defined by the height difference h1-h2, but that there is also a
change in the position of the wheel 1, for example the camber angle
c.
The wheel suspension arrangement is intended to be designed in such
a way that the wheel enjoys good contact with the surface on which
it is disposed, under all possible driving conditions, so that the
desired road-holding qualities of the vehicle are maintained. In
order to ensure that, the wheel position must adapt to the
movements of the wheel suspension arrangement, in regard to all the
wheel position parameters (tracking, camber, trail or caster and
steering swivel inclination). That is effected on the basis of
certain laws which are established by virtue of the dimensions and
the arrangement of the kinematic components of the wheel suspension
arrangement. Depending on the respective requirements which the
vehicle manufacturer seeks to fulfil in terms of the road-holding
qualities of the vehicle, the wheel suspension arrangements of
different vehicles differ greatly from each other in regard to
their geometrical data. In most cases, the geometrical data
involved are not known to the workshops which have to carry out
maintenance operations on such vehicles. Even if the geometrical
data in question are known, the geometrical performance of the
wheel suspension arrangement, as a function of different levels of
the vehicle, in consideration of loading and other factors, is not
known. Accordingly the vehicle manufacturers provide correlation
tables which contain the dependency of the wheel positions, more
particularly wheel angle positions, on the level of the wheel
suspension arrangement, and also set out reference values at which
wheel positions and in particular angular positions are to be
measured.
Besides the foregoing problems there is the point that the
operation of ascertaining the level of the suspension arrangement,
which involves measuring the spacing of the wheel suspension
arrangement from the ground on which the wheel is disposed, gives
rise to difficulties in ordinary workshops, in particular as
regards the accuracy which can be achieved in such a measuring
operation. In general the position in respect of height of the
ground or floor surface on which the wheel is supported cannot be
accurately ascertained in an inspection pit as inspection pits are
generally provided with upwardly projecting safety edges which
constitute an impediment to accurate measurement. It is therefore
generally necessary to rely on notional horizontal planes for
carrying out the measurement operations. There is therefore not a
standardised measuring method and the individual workshops manage
with such difficulties, as best they can.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a universal
measurement method for ascertaining a vehicle level so that same
can be reproducibly taken into consideration in a wheel position
measurement operation.
Another object of the present invention is to provide a method of
measuring wheel positions on a motor vehicle, such as angular
positions, which can provide highly reliable measurement results
and which can be readily employed in relation to a wide range of
different vehicle designs.
Still another object of the present invention is to provide a
method of measuring angular wheel positions on a motor vehicle,
which can be readily carried into effect in relation to
well-established reference or datum positions that are generally
easily accessible.
A further object of the present invention is to provide an
apparatus for determining wheel positions on a motor vehicle, which
can be integrated without difficulty into conventional wheel
position measuring systems.
Still a further object of the present invention is to provide an
apparatus for determining angular wheel positions on a motor
vehicle which can be easily fitted to a vehicle at a readily
accessible position.
In accordance with the principles of the present invention the
foregoing and other objects are achieved in a first aspect by a
method of measuring wheel positions on a motor vehicle, for example
for measuring given angular positions of a motor vehicle wheel,
wherein for the purposes of determining the level of the vehicle, a
plurality of different vertical spacings of a part of the body of
the vehicle from the center of the wheel, and the wheel positions
associated therewith are measured. The measurement values are
related to each other to define a dependency in respect of the
wheel position on the respective level.
In a second aspect of the invention the foregoing and other objects
are achieved by an apparatus for determining wheel positions on a
motor vehicle, comprising a detector for effecting angular
measurement operations, which detector is adapted to be fixed to
the motor vehicle wheel whose positions are to be measured, by way
of a suitable adaptor device. The apparatus further includes a
spacing measuring means for measuring an at least substantially
vertical spacing between the center of the wheel whose position is
to be measured and a part of the body of the vehicle.
Thus, the invention provides measurement of a plurality of
different vertical spacings of a body part of the vehicle such as
the outside edge of the mudguard or fender of the vehicle, from the
center of the wheel or wheel axis, and the wheel positions, in
particular angular positions, which are associated therewith. Those
different vertical spacings can be brought about for example by the
body of the vehicle being loaded to different degrees. In that
operation, account can be taken of the reference values which are
preset by the vehicle manufacturers in the tables that they issue.
The measurement values obtained are then related to each other in
order to ascertain a dependency of the position of the wheel, on
the level of the vehicle. In that way it is possible to determine
the correlations between the level of the vehicle and the position
of the wheel, in accordance with the specifications from the
vehicle manufactures. It is also possible however generally to
ascertain the dependency of the position of the wheel on the level
of the vehicle, for any type of vehicle, without the data from the
vehicle manufacturers.
As will be seen in greater detail hereinafter, the measurement
operation involves using the center of rotation of the wheel, or
the axis of the wheel, for determining the position of the unsprung
components of the wheel suspension arrangement. A part of the
vehicle body which is disposed thereabove in an at least
substantially vertical direction, more particularly the outside
edge of the mudguard or fender, is employed as the measurement
point in relation to the sprung components of the wheel suspension
arrangement. The wheel axis can be readily ascertained by means of
a conventional adaptor with which the detector for detecting the
wheel positions and more particularly angular positions is fixed to
the wheel in question. The level measurement operation can
therefore be readily integrated into the measuring procedure which
involves measurement of the wheel position.
The operation of determining the level of the vehicle is carried
out using a spacing measuring assembly for ascertaining the
vertical spacing between the center of the wheel which is defined
by the detector secured to the wheel by way of the above-mentioned
adaptor or by means of a component of the adaptor itself, and the
above-mentioned sprung part of the vehicle such as a part of the
body thereof. The detector and the adaptor are fixed to the vehicle
wheel in centered relationship. A self-centering adaptor may be of
assistance in that respect.
The detector to which the spacing measuring means is coupled is a
detector for wheel position measurement, for example for measuring
one or more of the wheel position parameters comprising tracking,
camber, steering swivel inclination and trail or caster. It is
possible for example to use any suitable detectors such as more
particularly those described in patent application Ser. No.
07/802,645 (U.S. Pat. No. 5,208,647) and patent application Ser.
No. 07/822,014 (U.S. Pat. No. 5,291,264) to which reference is
accordingly directed for incorporation of the disclosure thereof
into this specification.
Further objects, features and advantages of the present invention
will be apparent from the following description of a preferred
embodiment.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a diagrammatic view showing the position of a wheel with
associated wheel suspension arrangement, with a normal vehicle
loading,
FIG. 2 shows the structure of FIG. 1 with an increased loading on
the vehicle,
FIG. 3 shows a measuring arrangement constituting an embodiment of
the invention, and
FIG. 4 shows a block circuit diagram for evaluation of the signals
obtained with the measuring arrangement shown in FIG. 3.
DESCRIPTION OF THE PREFERRED EMBODIMENT
FIGS. 1 and 2 already having been described above to illustrate the
circumstances involved, reference will now be made to FIG. 3
showing a motor vehicle wheel indicated generally at 1, comprising
a disk wheel with a pneumatic tire fitted thereon. A wheel
suspension arrangement is provided in the usual way for definedly
mounting and guiding the wheel 1 relative to the main part of the
vehicle itself, for example the chassis structure, which is
referred to hereinafter as the sprung part 12 of the vehicle. The
wheel suspension arrangement is diagrammatically shown in FIG. 3
and comprises an upper strut or suspension link 15 and a lower
strut or suspension link 13. The upper suspension link 15 is
pivotally mounted to the sprung part 12 of the vehicle at a pivot
mounting location 18 and to an unsprung part 14 of the wheel
suspension arrangement, at a pivot mounting location 19. Similarly,
the lower suspension link 13 is pivotally mounted to the sprung
part 12 of the vehicle at a pivot mounting location 6 and to the
unsprung part 14 of the suspension arrangement, at a pivot mounting
location 7. The unsprung part 14 also carries a wheel hub assembly
16 to which the vehicle wheel 1 is fixed in known manner. The wheel
hub assembly 16 defines a wheel axis as indicated at M, which forms
the center of rotation for rotary movement of the wheel 1.
A detector 3 is fixed to the motor vehicle wheel 1 in defined
relationship relative to the wheel axis M by way of a
diagrammatically indicated adaptor 2 which can be of a generally
known configuration and which can possibly also be a self-centering
adaptor. The detector 3 is of any suitable construction, for
example of the kinds referred to above, and serves to measure the
position of the wheel 1, for example to measure the camber angle as
indicated at c. However it may also serve to measure further wheel
position angles, such as for example tracking, caster and steering
swivel inclination.
A spacing sensor 4 is coupled to the detector 3 so that the spacing
sensor 4 also occupies a defined position, relative to the wheel
axis M. The spacing sensor 4 can be disposed in the housing of the
detector 3. A suitable form of spacing sensor is a potentiometer,
such as more particularly a rotary potentiometer, which is
connected by way of a wire diagrammatically indicated at 20 to a
reference element 8 for example in the form of a rod or bar. The
reference element 8 is adapted to be fixed to a portion of the
vehicle which is rigidly connected to the main sprung part 12 of
the vehicle, more especially a portion of the body of the vehicle
such as the outside edge of the mudguard or fender, as indicated at
5, which is disposed at least substantially vertically above the
wheel axis M. The reference element 8 can be fixed in position for
example by means of a fixing screw. The extension length of the
wire 20 which is detected by the spacing sensor 4 is a measurement
in respect of the vertical spacing as indicated at b between the
outside edge of the mudguard or fender and the wheel axis M.
Through the presence of the wheel hub assembly 16 and the
suspension member 14, the wheel axis M is at a constant spacing
from the pivot mounting location 7, in respect of which the spacing
h2 from the ground 17 is a crucial consideration in the operation
of determining the level of the vehicle.
In addition, the part of the vehicle body to which the reference
element 8 is connected and which is disposed at a vertical spacing
above the wheel axis M, being therefore for example the outside
edge of the mudguard or fender, is rigidly connected in relation to
the pivot mounting location 6 which is the determining
consideration in regard to the spacing hi from the ground 17.
It will be seen therefore that, by determining the vertical spacing
b between the wheel axis M and the sprung part of the vehicle such
as the outer edge 5 of the mudguard or fender, it is possible to
obtain a dimension which is proportional to the level of the
vehicle as indicated at a and which is equal to (h1-h2). An
electrical signal which is proportional to the spacing b, that is
to say the level a, can be produced by the spacing sensor 4, and
will then be subjected to further processing, as will be described
in greater detail hereinafter.
Instead of an extensible wire 20 or a cord between the reference
element 8 and the spacing sensor 4 which in the illustrated
embodiment is in the form of a potentiometer, the spacing measuring
means may also be in the form of an optical spacing measuring means
using mirrors and light sources, in which case for example the
reference element 8 is represented by a mirror. In that case,
insofar as they are suitable for length measurement, the measuring
principles described in above-mentioned patent application Ser. No.
07/802,645 (U.S. Pat. No. 5,208,647) and patent application Ser.
No. 07/822,014 (U.S. Pat. No. 5,291,264) can be used.
Accordingly, the level a=(h1-h2) and also the wheel position can be
ascertained by the measuring assembly illustrated in FIG. 3. In
that respect level measurement is an integral component of the
wheel position measurement procedure. The level measuring assembly
comprising the components 4, 8 and 20 constituting the spacing
measuring means can be completely integrated into the measuring
arrangement of the detector 3.
The illustrated measuring arrangement can be used to ascertain
different level values, in relation to different vehicle loadings.
The various measurements can be carried out, having regard to the
vehicle manufacturer specifications, in which respect it is
possible to keep to certain reference data in respect of the
vehicle loading and/or various vehicle level values a0, a1 . . .
an.
It is also possible however, irrespective of the vehicle
manufacturer reference data, generally to determine different
values b0, b1 . . . bn in respect of the vehicle level (h1-h2), as
universally applicable values.
As was seen above in relation to FIGS. 1 and 2, it is not only the
vehicle level values but also the wheel position values and more
especially the wheel angle values that change. FIG. 2 shows the
change in the camber angle c. The change in the wheel position is
detected by the detector 3.
The values a0, a1 . . . an or b0, b1 . . . bn which are supplied by
the spacing sensor 4 and which are proportional to the level of the
vehicle, and the wheel position values c0, c1 . . . cn and d0, d1 .
. . dn supplied by the detector 3 are passed to a computer or
processor as indicated at 9 in FIG. 4, for further processing
thereof. References d0, d1 . . . dn identify the angle values which
do not correspond to the angle values which are preset by the
vehicle manufacturer, but which occur in each case with any
variations in level b0, b1 . . . bn. The values which are preset by
the vehicle manufacturer, for different levels a0 . . . an and
wheel positions c0 . . . cn can also be held in a store or memory
10 connected to the computer 9.
The computer 9 can for example carry out the following computation
operations:
thereby giving the relationship between the level value specified
by the manufacturer and the freely measured level value;
thereby giving the relationship between the wheel position
specified by the manufacturer and the level value specified by the
manufacturer; and
thereby giving the relationship between the freely measured wheel
position and the freely measured level position.
It is also possible to determine the relationship between a change
in the position of the wheel and a change in the level of the
vehicle, in which case the level and wheel position values
specified by the vehicle manufacturer can be used and/or the freely
measured universal values can be employed. It is possible for
example to compute the following relationships or correlations:
or
The various correlation values which are produced by the computer 9
can also be held in the memory 10 or in a separate store or memory
and are available for a further measurement value assessment
operation.
As shown in FIG. 4, the user can communicate with the computer 9 by
way of an interface 11. For that purpose the user may employ a
suitable input means such as an input keyboard. A printer or other
display means such as a display screen can be suitably connected to
the computer 9 by way of the interface 11. When using the
abovementioned parameters x, y, z and the correlations between the
change in wheel position and the change in level, and with the
specifications from the vehicle manufactures and also with the
values which can be measured in a workshop or generally, it is
possible to determine the dependency and more particularly the
non-linear dependency of the wheel position on the vehicle level,
and store it for example in the memory 10. Those correlations can
then be used again for further measurement operations in relation
to the respective specific types of vehicles.
In a preferred procedure the measurement operations may be carried
out at at least first, second and third different spacings between
the part of the body and the center of the respective wheel.
It will be appreciated that the above-described method and
apparatus according to the invention have been set forth solely by
way of example and illustration of the principles of the invention
and that various modifications and alterations may be made therein
without thereby departing from the spirit and scope of the
invention.
* * * * *